This invention relates to an apparatus for preserving at least one kind of liquid such as sample, reagent, buffer solution, and diluent to be delivered in an automatic chemical analyzer.
In a usual automatic chemical analyzer, in order to effect multi-item test, a plurality of reagents are preserved. Usually each reagents are contained in respective containers. There are two types of a reagent delivery mechanisms. In one type of mechanism, usually only one delivery device is provided and a given amount of a given reagent is aspirated into a probe and the aspirated reagent is discharged from the probe into a reaction vessel. In the other type, there are arranged a plurality of delivery devices, one end of each probe is connected to respective reagent container via a respective pump and a given amount of a given reagent is supplied through an entire length of the probe into a reaction vessel. In the former delivery mechanism, the reagent container has to be provided with an opening through which the probe passes, and thus, the reagent is liable to evaporate into a surrounding atmosphere through said opening. Contrary to this, in the later delivery mechanism, since such an opening is not required, the problem of evaporation does not occur. However, in the later mechanism, a number of delivery devices equal to the number of the reagent containers must be provided and the apparatus is liable to be complicated in construction and large in size. The present invention concerns the liquid preserving apparatus for use in a combination of the former type delivery mechanism.
In case of preserving the reagents in the analyzer, it is necessary to preserve the reagents in a cooling state in a temperature range of about 5.degree.-10.degree. C. for preventing the quality of reagent from being deteriorated. To this end, usually the reagent containers are arranged in a compartment and temperature in the compartment is lowered. However, since the air surrounding the reagent containers becomes low humidity in such a cooling state, the reagents are liable to evaporate and thus their concentrations might be changed. Moreover, in case that a plurality kinds of the reagents are arranged in the same compartment, there might occur such a drawback that acid components evaporated from the reagents might affect the quality of another reagents. Further the inside of the compartment might rust due to various components evaporated from the reagents.
In order to avoid the above mentioned evaporation, it has been proposed to seal the openings of the reagent containers with covers made of elastic material such as plastics and rubber, and the probe pierces the cover to suck the reagent. In such a case after the probe is removed from the cover, a hole in the cover is automatically closed due to its elasticity. However, in such a construction it is necessary to make the probe and a mechanism for supporting the probe mechanically strong. For instance, the probe must be made of metal and the probe holding device is liable to be large and heavy. Moreover, there is such a possibility that the probe might be clogged by chips of the cover, and this results in that a delivering precision becomes worse.
In U.S. Pat. No. 4,208,484, there is described an automatic culture system in which a space surrounding a centrifuge is shielded from the outer atmosphere and an opening through which centrifuge tube is passed is selectively closed by a movable cover. This system may be applied to the compartment of the reagent containers. That is to say, an opening formed in the compartment for introducing the probe may be closed by a movable cover. However, even in such a construction, the reagents might evaporate within the space and thus, the above mentioned problem could be overcome only to a limited extent.